A method and a device for controlling an internal combustion engine are described in German Patent No. DE 10305656. In the method described there, various characteristic variables are ascertained starting from signals of a structure-borne vibration sensor, which are used for the regulation of the internal combustion engine.
In the control and/or regulation of an internal combustion engine, especially a Diesel internal combustion engine, partially homogeneous and/or homogeneous combustion methods are used, which are characterized by a high exhaust gas recirculation rate in combination with an injection modified in comparison to conventional combustion for the achievement of a large ignition delay. Such partial homogeneous and homogeneous combustion methods are designated below as homogeneous combustion methods, or the corresponding operating state is designated as homogeneous operation.
What is problematic in such homogeneous combustion methods is that in response to transient processes, such as operation type switchovers or sudden load changes within the homogeneous operation, discontinuous curves with respect to engine torque and/or noise are able to occur. A common characteristic in these partial homogeneous and homogeneous combustion methods is that, compared to conventional combustion methods, greatly increased exhaust gas recirculation rates occur. For design reasons, this leads to charge compositions that are different from cylinder to cylinder, even at stationary operation. Conditioned upon manufacturing tolerances and aging effects of the fuel injectors and the overall system, this results in the taking of very different courses in combustion, which, in turn, cause very different pollutant emissions and noise emissions, individual to each cylinder.
Especially problematical is the stabilization of transient processes, such as a sudden load change, within a homogeneous operating range or an operating mode switchover between the conventional operation and a homogeneous operation.